glTF: How to optimize exported glb file from blender having more number of loop-cuts?
If your goal is a smooth appearance, you can use smooth normals to give the effect of a smooth surface with fewer loopcuts. If you are sure you need the loopcuts, your options are:


Disable export of normals, tangents, UVs, and any other per-vertex data you aren't using in the exporter settings.
The glTF format supports compression, but you'll have to apply it to the model after exporting from Blender. Use glTF-Pipeline to compress the model with the -d flag and you should see a file size reduction of 90-95% for models that contain primarily geometry.